Causes:

• abundance of silt eroded from the northern mountains into the dam areas

• deforestation on the foothills of the mountains

• the rivers in the mountainous areas wash down the eroded material into the plains which pile up in the reservoirs of the dams.

Effects:

• blockage of canals as silt piles up in the flow of water

• weakens the foundation of dams

• irrigation canals are also blocked which stops water flowing into the fields for irrigation

• the capacity of the reservoirs reduces and less water is stored which affects the generation of HEP and it also affects the amount of water flowing into the field areas for irrigation purposes

• risk of a flood is increased as the pressure on the walls of the dam is increased by the water and the excess mounds of silt

Large amounts of silt eroded from mountain ranges of Karakorum, Hindu kush and Himalayas

Deforestation. Continuous cutting of trees for different purposes and allowing more soil erosion

Rivers that come from deep and narrow valleys. They carry great amounts of silt and the eroded material is washed up to the plains. It then piles up in reservoirs of dams.

Effects

Silt accumulation blocks canals

It weakens the foundation of dams and reduces the reservoir capacity. This affects the production of hydroelectric power.

Reduces water for irrigation

Flow of flood water is hampered which may cause heavy damage to the dam because of the silt layers which block water flow